JPS5915359A - Picture contracting method - Google Patents

Abstract

PURPOSE:To contract a picture without causing the deterioration of picture quality due to drop-out of thin lines, by dividing a picture element train in the scanning direction of a white/black binary original picture in a prescribed length and then deleting a picture element from the longest run of each divided section. CONSTITUTION:A picture element train in the scanning direction of an original picture is divided into sections with each length of 7 picture elements. Thus white/black binary picture elements are obtained as shown in I -IV. The pictures are contracted in the following ruels. That is, (1) a picture element is deleted from the largest length of white and black runs of each section. In this example, a picture element of a black run 1 is deleted in a section I and a picture element of a white run 2 is deleted in a section II to obtain a picture element train as shown at the right; (2) a picture element is deleted from an optional run in case plural longest runs of the same color and same length exist as shown in the section III; and (3) a picture element is deleted from an optional white run in case plural longest runs of different colors and same length exist as shown in a section IV. These deleting actions are carried out by means of an ROM which functions as a conversion table.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to facsimile machines and the like, from pixel rows in the main scanning direction or sub-scanning direction of an original image.

The present invention relates to an image reduction method for obtaining an image obtained by reducing the original image by thinning out pixels at a predetermined ratio.

Conventional configuration and its problems In this type of conventional image reduction method, from each pixel column in the main scanning direction or sub-scanning direction of the original image, regardless of the appearance status of white pixels and black pixels in that column, , pixels were removed at regular intervals.

However, in the reduced image, periodic image unevenness, missing thin lines, etc. occur, resulting in a significant deterioration of image quality.Objective of the InventionThe present invention was made to eliminate the above-mentioned drawbacks of the conventional art. An object of the present invention is to provide an image reduction method capable of reducing an image without causing periodic image unevenness or deterioration of image quality due to missing thin lines. The image reduction method according to the present invention is achieved by dividing each pixel column in the main scanning direction and the sub-scanning direction of a black and white binary original image into sections each having a predetermined length.

An image obtained by reducing the original image is obtained by removing one pixel from each of these sections according to the 5th-order rules (a), (b), and (c).

(a) One pixel is removed from the longest run among the white run and black run in each section.

- If there are two or more runs of the same length in each section, and those runs are the longest runs, and those runs are of the same color, then remove one pixel from any one of the runs; (c) in each section, there are two or more runs of the same length, and those runs are the longest runs; If both a white run and a black run are included in the run, one pixel is removed from any white run among those runs.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. In the case of removing one pixel from , the above rules (a) and (b).

A specific example where (c) is applicable is shown below.

Next, the above rules will be explained using a specific example shown in Fig. 1. Section (a) above constitutes the basis of the above rules, and Figure 1 (1) and (II) show an example to which this section (a) is applied as is. ing.

That is, in FIG. 1(1), black run 1 with a length of 3 pixels is the longest run, so one pixel is removed from black run 1. Also.

In FIG. 1 (■), since the white run 2 having a length of 3 pixels is the longest run, one pixel is removed from this white run 2.

By removing one pixel from the longest run in this way, there will be no loss of thin black and white lines.

The first illustration shows an example where the above item (b) is applied. In this case, there are two longest runs. That is, black runs 3 and 4, which are two pixels long, are the black runs 3 and 4. In this case, removing one pixel from either of black runs 3 and 4 has the same effect on one image quality, so one pixel may be removed from either of the runs. This figure 1 (II
In I), one pixel is removed from the longest run that appears first, that is, black run 3.

Figure 1 (Goods) shows an example where the above item (c) is applied. That is, in this case, black run 6°7 and white run 6 are the longest runs (each 2 pixels long).
However, in this case, one pixel is removed from the white run 6. Since black pixels are the part that indicates information, there are two or more runs of the same length, and these runs are the longest runs, and there are white and black runs among these runs. If both are included, the effect on image quality can be reduced by removing one pixel from the white run among those runs.

Note that when pixels are removed according to rules (a), (b), and (c) above, the removal of pixels as a whole is performed at irregular intervals, so periodic image unevenness as in the conventional case is avoided. FIG. 2 shows a block diagram of a circuit for reducing an image according to an embodiment of the present invention. In this example, each pixel column in the main scanning direction of the original image is divided into sections each having a length of N pixels, and one pixel is removed from each section, so that N: (N-1). Assume that the image is reduced using the reduction ratio.

In FIG. 2, 8 is an original image input terminal for inputting pixel data b of the original image, and 9 is an N-bit serial input/parallel output shift register for inputting pixel take b from the original image input terminal 8. .

1101dRO, which stores a conversion table for converting the H-bit parallel data C output from the shift register 9 into (N-1)-bit parallel data q. Here, the parallel data q is obtained from N-bit parallel data C.
One hint is removed according to the rules (a), (b), and (c) above. Table 1 shows the conversion table when N=5 (0 indicates a white pixel, 1 indicates a black pixel)
.

In addition, in this conversion table, in cases where item (Cff) of the above rule applies, the run that removes one pixel is the longest run that appears first, and in cases where item (Cff) of the above rule still applies, , the run in which one pixel is removed is also the longest black run that appears first.

11 is an (N-1) bit parallel manual/serial output shift register which receives the output q of the ROM 10 as an input. 1
2 is a clock input terminal that inputs a clock a in synchronization with pixel data b; the clock a is input to a shift register 9, and at the same time drives the register 9;
It is also input to the control section 13. The control unit 13 changes the clock e that drives the shift register 11 from the -clock d.
and generates a load signal d for the register 11.

Table 1 Next, the operation of Jin's circuit will be explained with reference to the timing diagram shown in FIG. Pixel data b is input from an original image input terminal 8 to a shift register 9 in response to a clock a. Then, the parallel data C output from the shift register 9
Every time pixel data is input, ROM1
This is valid as an address input for o. Therefore, R.O.
M10 converts 7-bit parallel data C into 6-bit parallel data q using the conversion table and outputs it every time 7 bits of pixel data b are input.

The parallel data q is loaded into the shift register 11 by a load signal d, and the loaded data is serially output from the shift register 11 by a clock e.

Therefore, an image obtained by reducing the original image by a reduction ratio of N:(N-1) can be obtained from the output f of the shift register 11.

FIG. 4 shows a comparison of images obtained when an image of the kanji character "Omitted" is reduced by the present embodiment and the conventional method at a reduction ratio of 7=6 (in addition, from A3 size to 84 The reduction ratios when reducing the size to 84 size and from 84 size to A4 size are both approximated by 7=6).

In FIG. 4, (A) is the original image, (B) is the image reduced by the above-mentioned embodiment, and (C) is the image reduced by the above-mentioned conventional method (however, every seventh image of the original image is (obtained by removing the pixels of The entire image is reduced in a well-balanced manner, with little deterioration in image quality.

Reducing from A3 size to A41J is possible by first reducing A4 size to B4 size, and then reducing 84 size to A4 size, as you can see by reducing the 7:6 reduction ratio twice. good. FIG. 4(D) is an image obtained by further reducing the image (B) at a reduction ratio of 7:6 according to this embodiment, and (K) is an image obtained by further reducing the image (C) by a reduction ratio of 7:6 using the conventional method. In (R') K, which shows an image that has been reduced once again with the reduction ratio of Although there is some disturbance, the overall balance and characteristics of the characters are maintained, and it can be seen that there is still little deterioration in image quality.

Although the above embodiment is an example in which the present invention is applied to reduction in the main scanning direction, it goes without saying that the present invention can also be applied to reduction in the sub-scanning direction. The image reduction method provides an excellent effect in that images can be reduced without causing periodic image unevenness or deterioration of image quality due to missing thin lines.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a specific application example of the rules that determine which pixels are removed from an original image according to the present invention, and FIG. 2 is a block diagram of a circuit that implements an image reduction method according to an embodiment of the present invention. , FIG. 3 is a timing diagram of signals in the circuit, and FIG. 4 is a comparison diagram showing a comparison of reduced images obtained by the embodiment and the conventional image reduction method. 8... Original image input terminal, 9... Shift register +10... ROM-11...
・Schiff I...Register, 12...Re07 input terminal, 13...Control unit 8 Name of agent Patent attorney Toshio Nakao and one other person (Figure 4 1+ □ CB) (C) CD) (En

Claims (1)

[Claims] Each pixel row in the main scanning direction or sub-scanning direction of a black and white binary original image is divided into sections of a predetermined length, and from each section, the following (a) and (b) are divided. , (C) An image reduction method for obtaining an image obtained by reducing the original image by removing one pixel according to the rules of (c). (a) One pixel is removed from the longest run among the white run and black run in each section. (b) In each section, if there are two or more runs of the same length, and those runs are the longest runs, and those runs are of the same color, then Remove one pixel from any one of the runs. (c) In each section, there are two or more runs of the same length, and those runs are the longest runs, and those runs include both white runs and black runs. If so, remove one pixel from any white run among those runs.